In the world of woodworking, construction, forestry, and lumber trading, knowing how many board feet a log contains is essential. Whether you’re a sawmill operator, a timber buyer, or a DIY woodworker, estimating the correct amount of usable lumber helps with planning, pricing, and inventory control. That’s where the Board Foot Log Calculator proves incredibly valuable.
Board Foot Log Calculator
What Is a Board Foot?
A board foot is a unit of measure for lumber volume. It represents a one-foot length of a board that is 12 inches wide and 1 inch thick.
Formula:
mathematicaCopyEditBoard Foot = (Length in inches × Width in inches × Thickness in inches) ÷ 144 When dealing with logs, this measurement is applied using log scaling rules to estimate how much finished lumber can be milled from raw logs.
How to Use the Board Foot Log Calculator
To use this calculator, you typically need:
- Small-end diameter of the log (in inches)
- Length of the log (in feet)
Steps:
- Measure the diameter at the small end (inside the bark).
- Measure the length of the log.
- Select the scaling method (Doyle, Scribner, or International).
- Click "Calculate" to get the estimated board feet.
Board Foot Calculation Formulas
Several formulas are used in the industry, depending on your location and application.
1. Doyle Log Rule (popular in Eastern U.S.)
javaCopyEditBoard Feet = ((Diameter - 4)² × Length) ÷ 16 - Ignores taper and small logs
- Underestimates board feet for logs under 28 inches
2. Scribner Log Rule
javaCopyEditBoard Feet = (0.79 × Diameter² – 2 × Diameter – 4) × (Length ÷ 16) - Good for medium-sized logs
- Slightly more accurate for smaller logs than Doyle
3. International 1/4" Rule
bashCopyEditBoard Feet = ((0.049 × Diameter²) – (0.274 × Diameter + 0.622)) × Length - Most accurate and widely accepted
- Accounts for kerf and log taper
Example Calculations
Example 1 – Doyle Rule:
- Diameter: 20 inches
- Length: 12 feet
makefileCopyEditBF = ((20 - 4)² × 12) ÷ 16 BF = (16² × 12) ÷ 16 = (256 × 12) ÷ 16 = 192 Estimated Board Feet = 192 (Doyle) Example 2 – International Rule:
- Diameter: 18 inches
- Length: 16 feet
bashCopyEditBF = ((0.049 × 18²) – (0.274 × 18 + 0.622)) × 16 = (15.876 – 5.564) × 16 = 10.312 × 16 = 165 Estimated Board Feet = 165 (International 1/4”) Benefits of Using a Board Foot Log Calculator
✅ Time-Saving
Quickly determine lumber volume from raw logs with minimal manual calculations.
✅ Accurate Planning
Useful for inventory, mill output estimates, or pricing log lots.
✅ Choose Preferred Scaling Method
Use the method appropriate for your region or project.
✅ Financial Accuracy
Helps prevent overpaying or underselling logs in lumber transactions.
✅ Versatile
Works for logs of varying lengths and diameters across multiple applications.
When to Use This Calculator
- Buying or selling logs
- Logging and forestry planning
- Operating a portable sawmill
- Estimating material for woodworking or construction projects
- Teaching lumber volume in vocational or forestry programs
Helpful Measurement Tips
- Always use inside-bark diameter at the small end for accuracy.
- Use diameter tape for precision, or measure across two perpendicular axes and average.
- Make sure length is measured in feet and not converted unless specified.
- Round down odd lengths if your sawmill cuts standard lumber sizes (e.g., round 14.5 ft to 14 ft).
20 Frequently Asked Questions (FAQs)
1. What is a board foot?
A unit of lumber volume equal to 12″ × 12″ × 1″.
2. Why do we use the small-end diameter?
Because it reflects the minimum volume potential due to tapering.
3. Which log rule is most accurate?
The International 1/4" rule is considered the most accurate.
4. What’s the difference between Doyle and Scribner?
Doyle underestimates small logs; Scribner is better for medium logs.
5. Is this calculator good for hardwood and softwood?
Yes, the formula applies to both unless specified differently.
6. Can I measure logs in metric units?
You’ll need to convert to inches and feet before using most calculators.
7. Is bark included in the diameter?
No. Always use inside-bark diameter for accuracy.
8. What if my log is tapered?
The formulas account for taper by using small-end diameter.
9. Can I use this for standing trees?
Not directly. You’d need tree height and diameter at breast height (DBH) for tree volume estimates.
10. How do I measure diameter accurately?
Use a log diameter tape or calipers at the narrowest end.
11. Can I calculate multiple logs at once?
Yes—just repeat the calculation for each log and sum the totals.
12. Does log length affect accuracy?
Yes. Precision matters, especially for longer logs.
13. Why do sawmills prefer International Rule?
It provides realistic yield estimates considering kerf and taper.
14. What’s kerf?
The width of the saw blade cut, which reduces usable lumber.
15. Is this calculator suitable for portable mills?
Absolutely. It helps sawyers plan cuts and predict output.
16. Can I calculate in cubic feet or cubic meters?
Yes, but you’ll need a separate volume formula. This calculator estimates in board feet only.
17. Can I use this calculator on my phone?
Yes, most web-based calculators are mobile-friendly.
18. What size logs are not suitable for Doyle Rule?
Logs under 28 inches tend to be underestimated using Doyle.
19. Can I factor in saw waste?
The International rule already considers it. Others may not.
20. Is the calculator free to use?
Yes! It’s a free tool available online for anyone to use.
Conclusion
The Board Foot Log Calculator is a must-have tool for anyone working with raw timber—be it forestry professionals, lumber traders, or hobbyist woodworkers. It provides a fast, reliable estimate of the usable lumber volume in board feet based on simple log measurements.